BHP TORQUE CONVERSION

[Will McGonegal]

A typical work horse in James Watt's day could draw the equivalent of
550 lbs up one foot in one second (hence 550 ft-lbs/sec = 1 Horsepower).

If using units of revolutions per MINUTE - 550 ft-lbs/sec * 60 sec/min =
33000 ft-lbs/min
Because the motion is rotational (torque) and not linear 33000 / (2 *
pi) = 5252.11.... is the constant.

So: Torque [ft-lbs] = 5252.1.... * Hp / rpm.

Of course all this has been beaten to death before and is well
documented in the archives.